1. Field of the Invention
The embodiments of the present invention relate generally to modification and functionalization of metallic nanoclusters that incorporate organic compounds.
2. Background Information
The ability to detect and identify trace quantities of analytes has become increasingly important in many scientific disciplines, ranging from part per billion analyses of pollutants in sub-surface water to analysis of treatment drugs and metabolites in blood serum. Additionally, the ability to perform assays in multiplex fashion greatly enhances the rate at which information can be acquired. Devices and methods that accelerate the processes of elucidating the causes of disease, creating predictive and/or diagnostic assays, and developing effective therapeutic treatments are valuable scientific tools. A principle challenge is to develop an identification system for a large probe set that has distinguishable components for each individual probe.
Among the many analytical techniques that can be used for chemical analyses, surface-enhanced Raman spectroscopy (SERS) has proven to be a sensitive method. A Raman spectrum, similar to an infrared spectrum, consists of a wavelength distribution of bands corresponding to molecular vibrations specific to the sample being analyzed (the analyte). Raman spectroscopy probes vibrational modes of a molecule and the resulting spectrum, similar to an infrared spectrum, is fingerprint-like in nature. As compared to the fluorescent spectrum of a molecule which normally has a single peak exhibiting a half peak width of tens of nanometers to hundreds of nanometers, a Raman spectrum has multiple structure-related peaks with half peak widths as small as a few nanometers.
To obtain a Raman spectrum, typically a beam from a light source, such as a laser, is focused on the sample generating inelastically scattered radiation which is optically collected and directed into a wavelength-dispersive spectrometer. Although Raman scattering is a relatively low probability event, SERS can be used to enhance signal intensity in the resulting vibrational spectrum. Enhancement techniques make it possible to obtain a 106 to 1014 fold Raman signal enhancement.
A prerequisite for multiplex analyses in a complex sample is to have a coding system that possesses identifiers for a large number of analytes in the sample. Additionally, the identifiers, or reporters, for analyte detection may need to possess different properties depending on a user-selected application, such as for example, mechanical and/or chemical stability. Depending on the intended use, reporters may need to be chemically compatible with diverse applications, such as biochemical analyses and be capable of being stably functionalized over a variety of conditions with probes that allow for the complexation of the identifier with an analyte in a sample.